The 64-bit Cortex-A57 core is ARM’s latest and greatest CPU design, but very few chipmakers are actually building products based on this flagship core. In fact, many are skipping it altogether, so what’s going on here?

There is one thing to keep in mind. The Cortex-A57 is by no means a new design. In fact, it was announced in October 2012, with availability slated for 2014. As we all know, the rollout wasn’t very smooth and the only Cortex-A57 consumer part ready to ship in 2014 was the Exynos 7410 of Galaxy Note 4 fame. It was followed by the Snapdragon 810 and Exynos 7420, which hardly need an introduction.

Cortex-A57 is on almost schedule, so what’s the big deal?

While it is true that the Cortex-A57 was almost on time, our concern isn’t the rollout schedule – it’s the lack of designs. For a product announced 30 months ago, it has relatively few design wins and this is not going to change. In fact, at this point it is more or less obvious that a number of major SoC makers will skip it altogether.

Another relatively big player, Huawei HiSilicon, also appears to be skipping the A57. The company’s upcoming Kirin 940 and Kirin 950 parts should end up with Cortex-A72 cores instead. That’s not all, because some outfits like Nvidia have their own custom cores. Qualcomm is also expected to employ a custom core in the Snapdragon 820, while rumours of a Samsung custom ARMv8 core have been floating around for ages.

Thermal barrier and economics stall ARM SoC evolution

There are a few possible explanations for the lack of Cortex-A57 design wins, and they involve physics and economics.

From a technical perspective, the A57 requires too much effort and does not provide huge performance gains. Used in a big.LITTLE octa-core, the Cortex-A57 necessitates the use of four additional Cortex-A53 cores, a big GPU to match its potential, and the customary 4G modem found on high-end devices. All this results in a relatively big die with a lot of transistors, especially on planar nodes.

Snapdragon 810 layout - note the size of the GPU, modem, and other modules. The CPU doesn't look too big, but unlike other modules it is always utilised to some extent. Under load, the CPU and GPU are bound by the thermal envelope, which is not the case with the rest of the chip.

Thermal and power efficiency issues are another concern, as such a chip simply can’t reach its full potential on planar nodes, unless consumers suddenly become interested in buying big and thick phones, with oversized heatsinks and batteries.

The Cortex-A57 really isn’t an option at 28nm. It can, however, be successfully deployed on 20nm and 14/16nm FinFET nodes. This makes it an unattractive proposition for all but the most expensive devices, since it’s an elaborate design that requires an expensive, cutting-edge node to be implemented. By the time FinFET matures and foundry costs go down, ARM will already have another design to take its place – the Cortex-A72.

Cortex-A57 vs. Cortex-A72

The Cortex-A72 was announced in February 2015 and ARM expects to see it in commercially available devices by early 2016. Some chipmakers would like to get their hands on it even sooner, even using it on 28nm nodes rather than FinFET nodes it was originally designed for.

In some respects, the Cortex-A57 shared a similar fate to that of its predecessor, the Cortex-A15. The latter debuted on Samsung’s 32nm parts, but due to thermal issues the core wasn’t widely used until 28nm nodes became available (and cheap). However, it was all a matter of good timing – the A15 arrived just in time for 28nm, while the A57 sort of missed its window of opportunity.

Worse, Android 5.0 brought 64-bit support last year, prompting Google to tap Nvidia for its Nexus 9 tablet, as its Denver core was practically the only 64-bit ARM "big core" Google could use. Consumers could get affordable Cortex-A53 devices with 64-bit support, but they couldn’t get flagship 64-devoces. This may not be an important distinction for the average Fudzilla reader, since tech enthusiasts know 64-bit support simply wasn’t too relevant in 2014 (and still isn’t). However, it was a lot easier to market 64-bit parts based on small cores than big 32-bit cores.

So, will the Cortex-A72 end up with more design wins than the A57? Is it really much better than the A57?

Personally, I am inclined to say that the Cortex-A72 will be a lot more successful, not by virtue of its design, but thanks to better timing and the limited appeal of the Cortex-A57. ARM did not reveal a lot of information on the A72, other than to state that new core will be vastly more efficient than the A15 and A57, but its numbers were based on different nodes (28nm for A15, 20nm for A57, 16nm for A72).

We simply don’t know much about the Cortex-A72 yet and it's too early to jump to conclusions.

What does this mean for 2015?

Moving forward, the lack of a viable 64-bit ARM core for mid-range, and even some high-end devices on 28nm, is bound have a number of implications on the smartphone SoC market and smartphone design in general.

The Cortex-A57 simply won’t end up in a lot of devices, as it only makes sense on 20nm and 14/16nm FinFET nodes, so chipmakers will have only one choice – churn out more Cortex-A53 parts at higher clocks, with faster GPUs and better LTE support. Unlike last year, they don’t have the option of using four cores (A15, A17, A9 and A7), as they can only use A57 and A53 cores, but the A57 simply doesn’t work for most market segments. The Cortex-A17 looks like a very tempting alternative and MediaTek already tapped it for some parts, but this is a 32-bit core, positioned below the Cortex-A15 and Cortex-A57. While the A17 is a good performer with a good price/performance ratio, consumers demand 64-bit chips, plain and simple.

This will obviously have the effect of blurring the line between low- and mid-end devices, as many of them will have to share similar silicon – consumers will get A53 cores whether they’re buying a $100 phone or a $300 phone.

Companies like Huawei and MediaTek have already hinted at, or revealed chips designed to address the problem, by including four A53 cores at higher clocks (Huawei calls them A53e or enhanced cores). These cores will be backed by four slower A53 cores, and Qualcomm already uses such a layout in the Snapdragon 615.

When ARM announced the Cortex-A17 last February, the company made it clear that 28nm would provide “the most transistors per dollar” – this is still the case.

It is highly unlikely that any of these chips will be manufactured using expensive 20nm or FinFET nodes, at least not in the foreseeable future (at least four quarters, possibly five due to high demand for flagship chips in Q1 2016). Capacity is limited, cost will remain prohibitively high for months, and 28nm works just fine for Cortex-A53 parts. As a result, SoC designers are already doubling down on 28nm capacity, as it is obvious the node will have to soldier on well into 2016.

Even more 28nm Cortex-A53 designs with tweaked cores, updated graphics and modems.

Smartphone makers will have to devise new ways of differentiating non-flagship products.

Prices of mid-range devices are likely to drop.

No Cortex-A53 parts on 20nm or 14/16nm nodes.

28nm node will continue to dominate the mobile landscape for at least 4 quarters and start tapering off in the second half of 2016.

Soft demand for limited capacity FinFET nodes over the next 2-3 quarters due to lack of Cortex-A57 designs.

Intel could benefit from stalled ARM development.

There are a few caveats. Some small-core chips could make it to a new node later this year, but we are talking about niche products (perhaps some wearable SoCs, or in-house designs for certain low-volume smartphones). If demand for FinFET parts proves to be much lower than anticipated, it is possible that foundries will have to reduce pricing as more capacity comes online – but this depends on a wide range of factors and we doubt anyone can make a good forecast for at least the next quarter or so.

2015 will not be a very eventful year for the ARM SoC market, but it might turn out to be a race to the bottom.

While Qualcomm's 20nm Snapdragon 810 SoC might be the star of upcoming flagship smartphones, it appears that MediaTek has its own horse for the race, the octa-core MT6795.

Spotted by GforGames site, in a GeekBench test results and running inside an unknown smartphone, MediaTek's MT6795 managed to score 886 points in the single-core test and 4536 points in the multi-core test. These results were enough to put it neck to neck with the mighty Qualcomm Snapdragon 810 SoC tested in the LG G Flex 2, which scored 1144 points in the single-core and 4345 in the multi-core test. While it did outrun the MT6795 in the single-core test, the multi-core test was clearly not kind on the Snapdragon 810.

The unknown device was running on Android Lollipop OS and packed 3GB of RAM, which might gave the MT6795 an edge over the LG G Flex 2.

MediaTek's octa-core MT6795 was announced last year and while we are yet to see some of the first design wins, recent rumors suggested that it could be powering Meizu's MX5, HTC's Desire A55 and some other high-end smartphones. The MediaTek MT6795 is a 64-bit octa-core SoC clocked at up to 2.2GHz, with four Cortex-A57 cores and four Cortex-A53 cores. It packs PowerVR G6200 graphics, supports LPDDR3 memory and can handle 2K displays at up to 120Hz.

As we are just a few days from Mobile World Congress (MWC) 2015 which will kick off in Barcelona on March 2nd, we are quite sure that we will see more info as well as more benchmarks as a single benchmark running on an unknown smartphone might not be the best representation of performance, it does show that MediaTek certainly has a good chip and can compete with Qualcomm and Samsung.

Fudzilla has found out that the Samsung Galaxy S6 will be one of the first devices to boast a non-Intel chip build around a 14nm process.

The Exynos 7420 SoC will be a 14nm octa-core, with four Cortex-A57 cores and four slower Cortex-A53 cores. Most of the chips coming in 2015 will use ARM's big.LITTLE approach, but in 20nm. Samsung Exynos 7420 is 14nm and is also using Mali-T760 GPU. We have the manufacturing node confirmed by multiple sources but you only need to wait for the March 1 to see the official announcement at the Mobile World Congress Galaxy S6 launch event.

Qualcomm's Snapdragon 810 was the main candidate for the Galaxy S6, since Qualcomm has the best LTE modem on the market. However, Samsung pulled out from using the chip, sparking rumours that it was overheating. However it turns out that Samsung is simply happier with what it had in-house, and therefore decided to use the Exynos 7420 14nm octa-core instead. There is a chance that Samsung might use an external chip from Qualcomm, just as Apple does for iPhones.

The fact that Exynos 7420 SoC is 14nm means a few things. Samsung / GlobalFoundries 14nm manufacturing is in better shape than most people expected, as the Galaxy 6 is expected to sell in tens of millions of units this year. This is not some risk production 14nm for a low-volume phone that will sell in hundreds of thousands. Samsung trust its manufacturing capabilities with its best-selling, flagship phone.

Samsung is beating both Apple and Intel to market with a smartphone 14nm SoC. Apple is expected to use 14nm A8 with the new iPhone / iPads, but this traditionally happens in September / October. We expect to see Intel 14nm SoC showcased at Mobile World Congress but we are not sure who will use it. Intel had trouble getting high profile mobile phone manufactures interested in its smartphone technology.

From what we can see in early benchmarks, the 14nm Exynos 7420 won't be much faster than the 20nm Exynos 5433 predecessor in any tests except in 3D. It turns out that you can expect more than 20 percent faster graphics and significantly faster runtime test in AnTuTu. The 14nm SoC should be good in terms of battery life too, as 14nm should need 35 percent less energy to work at the same clocks. Samsung is promising that its 14nm LPE (Low Power Enhanced) manufacturing process can give some 20 percent of performance increase compared to 20nm SoCs.

The 2015 will be an interesting year for phones as Samsung has a new weapon and the rest of the industry has to rely on Snapdragon 810 or MediaTek processors for 2015 performance and high end phones.

Rockchip has acquired a new subscription license for a broad range of ARM technologies and designs.

The deal gives the Chinese chipmaker access to ARMv8-A, along with Cortex A57 and A53 processors. Rockchip has also licensed the ARMv7-based Cortex A12 and ARM’s Mali GPU family as well as ARM CoreLink interconnect technology.

“This subscription license of ARM technologies enables us to continue building a comprehensive technology and product roadmap, demonstrating our commitment to enabling the next-generation Smartphone, Tablet, Android Notebook, Phablet and

Internet TV products with higher performance and power efficiency for consumers across the globe,” said Feng Chen, Chief Marketing Office, Rockchip.

Rockchip currently produces a range of dual- and quad-core A9 parts and it is expected to launch its first A12 part early next year. Interestingly, Rockchip does not do A7-based parts like many competitors, such as Mediatek.

However, the licensing deal will allow it to come up with A53 products and the A53 is practically ARM’s 64-bit successor to the A7.